1. Katy Perry is an American singer-songwriter from Santa Monica, California. She is most notable for her singles, "UR So Gay", released in 2007, and the song, "I Kissed a Girl", which was released in 2008, by Capitol Records
2. To tell a person off via a song insinuating their sexual preference
"Ur So gay" was Katy Perry's way of getting back at an old flame.